Glass container for light operated electric switches



M y 1931. R. w. ARMSTRONG ETAL 1,805,966

GLASS CONTAINER FOR LIGHT OPERATED ELECTRIC SWITCHES Filed Sept. 20, 1926 2 Sheets-Sheet l INVENTORS IRA. E. n cnbz. BY onp w Ammonia ATTORNEYS.

'l llI/III/III/lIII/IIIIIIIIIIIIIlIt/IIIIIIIIIIII/ May 19, 1931. C

R. W. ARMSTRONG ET AL 1,805,966 GLASS CONTAINER FOR LIGHT OPERATED ELECTRIC SWITCHES Filed Sept. 20, 1926 2 Sheets-Shet 2 & v 4

a A TTORNEYS.

Patented May 19, 1931 UNITED STATES PATENT OFFICE RAYMOND W. ARMSTRONG- AND IRA E. MGGABE, OF CHICAGO, ILLINOIS; SAID ARMSTRONG ASSIGNOR TO THE ARCLESS CONTACT COMPANY, A CORPORATION'OF rumors GLASS CONTAINER FOB. LIGHT OPERATED ELECTRIC SWITCHES Application filed September 20, 1926. Serial No. 136,504.

This invention relates to improvements in manufacture of glass articles and more particularly to the formation of glass containers for light-operated electrical switches.

Heretofore switches of this character have 7 been constructed homogeneously by forming a bulb similar in shape to the commercial electric light bulb at each end of a glass tube and bendin the tubular connection between the enlarge ends in the form of a V, placing sufficient mercury in the restricted tubular connection to form a seal between the enlarged end portions at the bottom of the V and before the bulbular ends are sealed inserting an electrode in each bulb and sealing the electrodes therein, one electrode normally immersed in the mercury seal and theother terminatedabove thesurface thereof, and then coating the bulb containing the immersed electrode with lamp black or other'adiathermanous substance whereby when the switch is exposed to light from the sun, flame, electric light, or other source, the radiant energy therefrom will be absorbed by the covered bulb which will increase the temperature of its walls and cause the expansion of the contained gas creating a pressure therein greater than that in the other bulb, thereby forcing the mercury seal to ascend in the leg ofthe V adjoining the other bulb and form an elec trical connection between thetwo electrodes. Upon the removal of the source of radiant energy, the increased temperature in the walls of the covered bulb will be radiated into the surrounding atmosphere, and as the pressure becomes normal in that bulb the mercury seal will descend to its normal level and break the electric connection.

This invention contemplates an improvement in the above-described construction and relates to the inter-connecting portion, which will require less mercury for the seal between the bulbs and which will be more sensitive to smaller changes in pressure to actuate the switch, the manner in which the electrodes are positioned in the switch, and also to the manner' in-which the bulbs are formed whereby bulbs of 'diflerent character of glass may be employed in place of coating one with adiathermanous covering, as above described;

While the preferred forms of this invention are illustrated in the accompanying sheets of drawings, yet is to be understood that minor detail changes may be made without departing from the scope thereof.

In the drawings:

Figure 1 is a view in front elevation of a switch casing containing an embodiment of this invention shown in vertical section.

Figure is a view in side elevation of Figure 1 illustrating the walls of the casing in vertical section.

Figure 3 is an enlarged detail view illustrating one form of welding of a bulb of different character to the interconnecting section of the switch.

Figure 4 is a similar view of another form of connection.

Figure 1 is a view of this improved lightoperated electric switch looking into the open front of the switch casing 1 and illustrating the bulbs 2 and 3 with their interconnecting portion 4 in vertical central section. From this view it is seen that both bulbs follow the general contour of the commercial electric light bulbs and are similarly arranged on each side of the vertical central line of the casing, with the interconnecting portion in the form of a short wide U. The bulbs and interconnecting portions are secured to the back of the casing by clips 5, the back of the casing is also provided with binding posts 6 to connect the switch in the desired circuit.

In accordance with this invention, the intel-connecting portion 4 maybe formed integral with the bulbs 2 and 3, if desired, and is provided with an extremely small bore 7 in the form of a capillary tube which is ex- 'panded at each end into cup-like portions 8 ily seen that it will take. but a very small amount of increased or decreased pressure 1n one bulb to increase or decrease the level of the liquid seal in the cup portion of the other bulb. I

This invention also contemplates the insertion of the electrodes 10 into the same bulb, preferablyby forming a re-e-ntrant section 11 in the wall thereof at the upper end of the bulb and holding the electrodes in separated relation to each other by sealing into the reentrant portion as shown. The electrodes may be of the same length, each terminating above the surface of the mercury in the cup portion 8 of that bulb,'as shown, both immersed in the mercury, or one immersed and theother out of contact therewith, as desired in accordance with the nature of the switch.

' The exterior terminals of the electrodes 10 are connected preferably by flexible leads 12 to the binding post 6 on the back of casing.

While either bulb may be of afmedium" adapted to absorb greater energy from the rays of light falling upon it than the other bulb, Figure 1 illustrates the electrodes 10 both terminated in proximity to the surface of the mercury incup 8 of the bulb 3 supporting the electrodes and the other bulb 2 of the medium adapted to absorb the greatest energy when subjected to light. Inv this construction, the switch is constructed normally to maintain the level of the mercury out of contact with the electrodes and the circuit between the binding posts opened. YVhen the switch is subjected directly to the rays emanating from any source of light, the walls of bulb 2 will absorb more energy therefrom than bulb 3, increasing the temperature of its walls and correspondingly increasing the pressure of the air or gas therein above the surface of the mercury in cup 8, whereupon as the pressure increases beyond that in the other bulb, the mercury will be caused to pass through the capillary tube 7 and increase the height of the mercury in cup 8 of bulb 3 until the ends of both electrodes 10 are immer sed therein, thereby forming an electric connection between them and closing the circuit between the binding posts 6. lVhen the source of radiant energyis removed, the increased temperature of the walls of bulb 2 is dissipated into the surrounding atmosphere and as the temperature approaches that of the other bulb, the pressure in the two bulbs equalizes and the mercury level in the two cups become normal with the result that the connection between electrodes 10 and likewise between the binding posts 6 is broken.

It has been found that while glass is most adaptable for the material forming the bulbs and interconnecting portion, different characters of glass possess diflerent absorbing properties. Transparent glass that will transmit all of therays of the visible spectrum absorb more or less of some of the invisible rays of light, and likewise colored glasses absorb the rays of the visible spectrum not reflected or transmitted to form the color produced and in so doing absorb the energy of such rays and increase the temperature of the colored glass. While the forming of one bulb of a clear transparent glass and the other bulb of a ooloredglass to produce a lightoperated switch as above described, is not broadly the subject of this invention, the man- 7 ner of connecting such switches including bulbs of differentcharacters of glass in the manner hereinafter described is originally contemplated in this invention. Glasses of difierent character possess different coeifigo cient, of absorption when subjected to light so that a union between two glasses of widely different coefiicients of absorption and subjecting such joined or united glasses to light would cause an unequal absorption or unequal heating of the two sections resulting in unequal expansion causing a rupture, fracture or cracking of the glass at the joint or union. This invention contemplates a manner of forming a union between such glasses that will withstand the unequally absorbed heat to which a switch of this character would be subjected in the performance of its'normal duties and this invention furthermore contemplates the formation of different types I of unions in accordance with the different amounts of absorbed heat normally encoun-, tered according to the use for which the switch is desired. x

Figure 3 illustrates the construction of one form of this improved union. It has been found that when a surface. of glass, either clear and transparent or colored, receives the rays of radiant energy, either visible orinvisible, at right angles to its surface, the ratio of absorption is greater than when the same rays impinge at an angle upon the same surface, as in the latter case part of the rays are reflected. In the form illustrated in Figures 1 and 3, the enlarged bulb portion 2 is shown with the dimensions of the body as it ap proaches the cup 8 rapidly decreased so that the outer surface 13 of the walls forms an obtuse angle therewith and presents a distinctly flat angular surface to the horizontal. plane of sufficient area to reflect an appreciable number of the horizontal visible rays im pinged thereon resulting in less absorption by.

the walls at the angular surface than by the larger slightly curved wall surfaces thereabove, receiving the horizontal light rays with but little reflection. The result is that the bottom of 'theangular portion may be welded to a clear or transparent glass connecting portion having either a similar or different coefiic-ient of absorption than the colored bulb and the normal operation of the switch will not cause a crack, fracture or break at the union because the increase in temperature in the walls of the colored bulb caused by the absorption of rays in the visible spectrum when the switch is exposed to visible light is gradually decreased by angular surface 13 as it approaches the cup 8 and therefore decreases the amount of expansion of the colored walls as they approach the point of union.

Another means contemplated by this invention to produce the same results is illustrated in Figure 4 in which the diiference in range of coefficients of absorption of the connecting portion 4 and the walls of the colored bulb 2 is of such a wide range that a suflicient decrease in absorption of the colored bulb cannot be readily obtained by the provision of the angular surface 13, above described, to prevent a break, fracture or crack on the operation of the switch at the joint or union. In such a case a section of glass 14 having a coefiicient of absorption intermediate to the coefiicients of the parts desired to be united is interposed between the bulb 2 and the connecting tube 4, being welded at one end to the bulb and at the other end to the connecting tube 4 or cup 8, whereby when the switch is exposed to light the temperature of the walls of the bulb is increased by absorption and the walls expand, the same light falling on the intermediate section will cause it in turnto expand sufliciently on accountof its coeflicient of absorption to cause the union to the bulb to remain intact. The increase in temperature in the intermediate section at its union to the bulb will be transmitted through, the body of its walls to the union of the connecting tube or cup, however, suflicient heat will be dissipated during its travel through the intermediate section from its union to the bulb to its union to the connecting tube or cup to allow the union cup or tube to remain intact. If necessary to establish a more perfect union, two or more intermediate sections of graduated c'oeificients of absorption may be interposed between the walls of the body having the increased coefiicient and the walls of the body having a lesser coefficient and thereby allow a welding of the parts together so that upon subjecting the united parts to light a graduated increase in temperature is produced so that, by the proper selection of media of the sections, no one will be expanded enough to break, fracture .or crack the union between it and the contiguous part.

While glass is transparent and transmits the visible rays of li ht in varying degrees in accordance with t e composition of the glass most glasses are opaque to the rays of the invisible spectrum, also in varying'degrees in accordance with the composition of the glass. The rays of light, both visible and invisible, impinging upon the body of glass that are not transmitted through are reflected from its surface or absorbed, the absorbed rays converted or transmuted into come heated to different degrees and therefore expand unequally and likewise glasses having the same coeflicient of absorption but diiierent coeflicients of expansion when subjected to rays of light will become equally heated but expand unequally.

By this invention switches of the character described may be formed by joining glasses having difierent coeflicients of absorption and yet produce a union that will not be disrupted by too great a difierence in expansion between the two glasses when performing the function for which they are designed.

What. we claim is:

1. In a visible light-operated mercury tube switch, two interconnected gas containers having a portion of lesser diameter connect- 9 ing the end portions and adapted to contain a mercury seal therebetween, the end portion of one container having a greater coefiicient of absorption of visible light than the contiguous connecting portion, said end portion conically tapering into the said connecting portion presenting an angular surface adapted to reflect rays of light impinging on the said container. 2. In a visible light-operated mercury tube switch two interconnected gas containers having a portion of lesser diameter connecting the end portions and adapted to contain a mercury seal, one end portion havin a greater coeflicient of absorption of visible light than the connecting portion, and a medium having an intermediate coefficient of absorption of visible light interposed between the enlarged end portion and connecting portion.

RAYMOND W. ARMSTRONG. t

'IRA E. MOCABE. 

